In a large pot over medium heat, add strawberries, rhubarb, water, and lemon and bring to a boil.

Reduce the heat to medium-low an simmer for 5 minutes, stirring occasionally.

Add sugar and continue stirring occasionally, until jam has thickened about 10-15 minutes.

Skim off any foam that's formed on the surface and discard.

Dived the jam between 4 sterilized half-pint jars. Wipe down rims with a clean cloth, then screw the lids on until they are finger tight. 

Fill a large pot with water about 2/3 full,  (a pot taller than the pint jars and big enough to hold all four), and bring to a boil.

Place the jars in the boiling water using a jar lifter and boil for 15 minutes. 

Remove from the water and place on a cutting board. Most jar lids will pop shortly after removing the jars. This signifies the lids have vacuumed sealed.   If they don't seal within a half hour then place in the fridge and enjoy. 

The sealed jars can be stored for up to a year.